Reference error window not defined error in Web3

Question

Here is my code:

import Web3 from './web3';

if (window.ethereum) {
    window.web3 = new Web3(ethereum);
    try {
        // Request account access if needed
        ethereum.enable();
    } catch (error) {
        // User denied account access...
    }
} else if (window.web3) {
    // Legacy dapp browsers...
    window.web3 = new Web3(web3.currentProvider);
} else {
    // Non-dapp browsers...
    console.error('Non-Ethereum browser detected. You should consider trying MetaMask!');
}

export default window.web3;

I am getting the error as:

Server Error Reference error Window not defined

Getting error at line:

window.web3 = new Web3(ethereum);